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A query which puzzles me:
(1) In Einstein's Clock shown moving through Space, the light is shown travelling vertically between the moving mirrors. Since the light travels through Space independently of the Clock and will receive no impetus from the movement of its source, from whence does it get the same magnitude and direction of movement relative to external Space as the mirrors? Therefore why does it not appear to move rearwards over a longer path relative to the mirrors rather than being carried forwards relative to the stationary observer?